[Sandy Bridge] So what does VccSA and VccIO actually do?

I've been playing with 2600K for a few days now.It seems that my 2600K's sweet spot is around 47 * 100 = 4.7GHz. It's LinX 50 loops stable but would fail Prime95 in 20 minutes (BSOD 124).

I wonder what VccSA and VccIO actually do and its importance. Which one powers the IMC? Some says it's VccSA while others say VccIO. :confused:

Here's my rig setup and some configuration I've made.

Core i7 2600K [L041B]
Asus P8P67 Pro Bios 1003
G.Skill 16000CL6D-4GBPIS @1866 6-9-6-24 1T
EVGA GTX580
Thermaltake 750w


Multiplier: 47 (bench-able @5.0GHz vcore 1.42)
BClk: 100
Vcore: 1.355 - 1.360
Load Line Calibration: Ultra High (Lower than this cause instability/huge Vdroop under load, Extreme= exceed the voltage set in BIOS under load)
CPU Capability: 120% - 130%
VccIO: Auto
VccSA: 0.975
Vdimm: 1.65v
PLL: Auto
Phase Control: Optimized
Long Duration Power Limit: 120 - 130
Short Duration Power Limit: Auto


:confused:

Current Max bench-able
http://valid.canardpc.com/cache/banner/1590128.png

0x124 = add/remove vcore or QPI/VTT voltage (usually Vcore, once it was QPI/VTT)

Refer to this tread for more info http://www.xtremesystems.org/forums/...d.php?t=264847

Quote:

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Originally Posted by skeyo

0x124 = add/remove vcore or QPI/VTT voltage (usually Vcore, once it was QPI/VTT)

Refer to this tread for more info http://www.xtremesystems.org/forums/...d.php?t=264847

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yeh, but which one is the QPI/VTT? VccSA or VccIO? :confused:

VCCIO=qpi/vtt/IMC voltage, don't touch VCCSA that is the system agent voltage, its supposed to be fixed :) i mentioned it in my guide :)

I think I figured out the reason BSOD 124 keep occurring when I do Prime95.

The LLC is set at Ultra High in order to maintain the vcore at 1.360-1.344 under load (LLC @High causes BSOD 101). My guess was that the VccIO is affected by the high LLC level so I lowered the VccIO to 1.03750 (Default 1.050) and set VccSA back to its default at 0.9250.

Now it's been 30 minutes without BSOD on Prime95(Mem @1866 6-9-6-24 1T). I'll keep you posted for the result.

I've had the very same 101 BSOD with my 2500k. I'm not sure how effectively a vdrop mod would cause a clock interrupt timeout, but my guess would be because the LLC is forcing the CPU to run out of spec voltage. Simply relaxing LLC should fix the issue.

Quote:

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Originally Posted by sin0822

VCCIO=qpi/vtt/IMC voltage, don't touch VCCSA that is the system agent voltage, its supposed to be fixed :) i mentioned it in my guide :)

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Why not? I've been running 0.80V which is the lowest without problems for a whole day now.

http://hardforum.com/showthread.php?t=1578110

Quote:

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This has shown in internal testing not to improve overclocking, yet may still maintain the same level of stability while being lowered from its default value in order to keep the CPU cooler.

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http://www.xtremesystems.org/forums/...d.php?t=264300

By my experience these 3 voltages do not affect stability at all, if you can boot, you are good, these are my settings:
VCCSA Voltage: 0.80000
CPU PLL Voltage: 1.51250
PCH Voltage: 0.91000

Note that I'm running LLC Regular (0%), which BTW is the easiest to overclock with, and requires lowest load voltage.
So start with regular and raise voltage until you are 10min Prime stable, then you shouldn't need more than 1 notch to be completely stable.

Vssa mem controller - like nb
Vccio Stabalize Rtl

BSOD 124 & 101 is very common for my 2600K

124 and 101 are both too low Vcore, 124 is more common, only got 101 in LinX.